1. Field of the Invention
The present invention relates to drywall tapes for finishing drywall joints and, more specifically, to drywall tapes having non-uniform cross-sections, to drywall tape applicators and to methods of finishing drywall joints.
2. Brief Description of the Prior Art
In the field of building construction, wall surfaces are typically formed by flat sheets or panels of drywall affixed to underlying support or frame members. The drywall sheets are typically available in a limited assortment of standard sizes, such as 4 feetxc3x978 feet; and, accordingly, a plurality of drywall sheets must be secured to the frame members in adjacent or abutting side-to-side, end-to-end and/or side-to-end relation in order to form a wall surface of larger dimension. Adjacent drywall sheets are placed as close as possible to one another and, preferably, in abutment with one another. Even though the adjacent drywall sheets are placed as close to one another as possible, a gap or groove is presented between adjacent or abutting side and/or end edges of the sheets. As a result, drywall joints are formed along the adjacent or abutting side and/or end edges of adjacent or abutting drywall sheets. Furthermore, the side edges of conventional drywall sheets are typically provided as xe2x80x9cfactory edgesxe2x80x9d in that outer surfaces of the drywall sheets, respectively, have non-sloping outer surface portions, respectively, and sloping outer surface portions, respectively, that slope inwardly from the non-sloping outer surface portions to the side edges. Accordingly, when the factory edge of a drywall sheet is adjacent or in abutment with the factory edge of another drywall sheet, the sloping outer surface portions cooperate to form a shallow depression along the thusly formed joint, the depression having a width extending between the non-sloping outer surfaces portions of the drywall sheets, respectively. An individual wall surface will typically have numerous joints, which interrupt the continuity of the wall surface and present an unattractive appearance. If left unfinished, the joints would be visible through the final wall finish, such as paint, wallpaper or other decorative coating, applied to the wall surface.
Conventional building construction techniques involve finishing the joints formed by adjacent or abutting drywall sheets so as to render the joints as invisible as possible after application of the final wall finish. The joints are finished conventionally using a paper drywall tape, such as Sheetrock(copyright) Joint Tape manufactured by U.S. Gypsum Company of Chicago, Ill., secured over the joints with joint compound or xe2x80x9cmudxe2x80x9d, an aqueous, cementitious adhesive. Conventional drywall tape is approximately 2 inches in width and is of uniform minimal thickness. The tape is supplied in rolls of various lengths ranging, for example, from 75 feet to 500 feet. According to conventional wall finishing techniques, an initial or bedding layer or coat of joint compound is applied over the joints, and the drywall tape is thereafter applied to the joints over the initial or bedding coat of joint compound. When applying the drywall tape, the width of the tape is centered or substantially centered over the corresponding joint so that the tape bridges the gap or groove thereof and is secured to the outer surfaces of the adjacent or abutting drywall sheets, respectively, forming the joint. The bedding coat of joint compound serves the purposes of filling the gaps of the drywall joints, filling the depressions formed at the joints by the sloping outer surface portions, i.e. the factory edges, of the adjacent or abutting drywall sheets and securing the drywall tape to the outer surfaces of the drywall sheets.
After the joint compound has dried, another layer or coat of joint compound is applied over the tape, in a step known as xe2x80x9cblockingxe2x80x9d, to smoothly blend or merge the tape with the non-sloping outer surface portions of the drywall sheets. Conventional xe2x80x9cblockingxe2x80x9d involves applying the layer or coat of joint compound as a band or stripe extending along the corresponding joint, the band or stripe being of greater width than the width of the drywall tape so that the joint compound serves to blend or merge side edges of the tape into the non-sloping outer surface portions of the drywall sheets. Usually, the band or stripe is applied so as to have a width of approximately 8 to 10 inches for drywall tape that is 2 inches wide, with the width of the band or stripe being centered or substantially centered over the width of the drywall tape. The joint compound is allowed to dry; and, thereafter, one or more additional layers or coats of joint compound is/are applied over the joints in a step known as xe2x80x9cskimmingxe2x80x9d to render the joints as indistinguishable as possible from the non-sloping outer surface portions of the drywall sheets. The joint compound must typically be allowed to dry between application of the individual coats or layers; and, when dry, the individual coats or layers of joint compound must typically be sanded to obtain a smooth surface merging or blending imperceptively with the non-sloping outer surface portions of the drywall sheets. In addition, the joints usually must be cleaned between the application of individual coats or layers of joint compound in order to achieve the best results. For example, it is desirable that the joints be cleaned to remove dust or other surface debris, such as that generated by sanding.
Wall finishing in accordance with conventional procedures is costly and time consuming due to the materials and labor required. In particular, the need for several coats or layers of joint compound and the need for relatively wide bands of joint compound to xe2x80x9cblockxe2x80x9d the joints adds to the cost of construction. Since the coats or layers of joint compound must be allowed to dry prior to sanding and/or the application of additional coats or layers thereover, it may take several days to finish a wall for painting, papering or other final wall finish. The time required for conventional wall finishing as well as the labor involved in executing the various wall finishing steps further increase the cost of construction.
In addition to the substantial time and cost required, conventional wall finishing techniques also require considerable skill and expertise. It is important, for example, that the tape lay uniformly or evenly as flush or flat as possible with the non-sloping outer surface portions of the drywall sheets and that the tape be sufficiently secured to the drywall sheets to prevent buckling or peeling of the tape. It is also important that the tape not be wrinkled and that there be no air bubbles under the tape. The finished drywall joints should not present abrupt variations in level but, rather, should be imperceptible after the application of paint, paper or other final wall finish. Additionally, the finished joints should not produce shadows or other visual irregularities under various lighting conditions. It is essential, therefore, that the right amount of joint compound be applied to the joints in the correct manner for each layer or coat. Furthermore, the drywall tape must be skillfully applied over the bedding coat of joint compound. In addition, the individual coats or layers of joint compound must be allowed the proper amount of time to dry prior to the application of additional coats or layers of joint compound and/or prior to sanding in order to ensure the aesthetic and structural integrity of the joints. Since application of the joint compound, particularly the xe2x80x9cbedding coatxe2x80x9d, to the joints is messy, care must be taken to avoid getting the joint compound on drywall surfaces other than those intended to have the joint compound applied thereon. Furthermore, the joints must be sanded with care. It is apparent, therefore, that the quality of finished drywall joints obtained with conventional wall finishing techniques is greatly dependent upon the skill and expertise of a particular wall finisher and is thusly subject to human differences.
Even where drywall joints are skillfully finished in accordance with conventional wall finishing techniques, such joints nonetheless present various additional drawbacks. In particular, the drywall tape tends to be undesirably drawn or sucked into the gap or groove between the adjacent or abutting edges of the drywall sheets and/or into the depression formed by the sloping outer surface portions, i.e. the factory edges, of the adjacent or abutting drywall sheets forming the corresponding joint. When this occurs, the joint is impaired upon being finished in that the finished joint is no longer smooth and even with the non-sloping outer surface portions of the drywall sheets and is prone to cracking. Another drawback of conventionally finished joints involves cracking that occurs at such joints in response to natural contraction and expansion of the associated wall or walls. As a result of such cracking, the joints as well as the paint, paper or other final finish of the wall or walls will typically require repair or corrective measures to be taken in order to restore the appearance of the wall or walls. However, such cracking tends to reoccur. A further drawback of conventionally finished drywall joints is that such joints are frequently impaired due to environmental conditions present during the finishing procedure. Wall finishing frequently takes place in partially completed, unheated structures; and, depending on the temperature and/or humidity present during conventional wall finishing procedures, the quality of the joints finished thereby may be less than desirable even where a high level of skill and expertise has been exercised.
Various drywall tapes have been proposed in order to facilitate wall finishing as illustrated in U.S. Pat. No. T887,014 to Overbay et al., U.S. Pat. No. 1,751,327 to Haire et al., U.S. Pat. No. 2,064,785 to Crandell, U.S. Pat. No. 4,042,739 to Emal et al., U.S. Pat. No. 4,313,991 to Lamb, U.S. Pat. No. 4,792,473 to Vitale, U.S. Pat. No. 5,246,775 to Loscuito, U.S. Pat. No. 5,486,394 to Stough, U.S. Pat. No. 5,604,001 to Schold, U.S. Pat. No. 5,687,523 to Stough and U.S. Pat. No. 5,711,124 to Stough et al.
The Overbay et al., Emal et al., Lamb, Vitale, Loscuito, Stough (""394 and ""523), Schold and Stough et al. patents all relate to adhesive drywall tapes for direct application to drywall joints without the need for a xe2x80x9cbedding coatxe2x80x9d of joint compound.
Emal et al. disclose an adhesive drywall tape having a synthetic resin-based adhesive. Adhesive drywall tapes having an acrylic adhesive are disclosed by Vitale, Loscuito, Stough (""394 and ""523) and Stough et al. Adhesive drywall tapes having a hot melt adhesive are disclosed by Overbay et al. and Schold.
In Overbay et al., the hot melt adhesive is disposed on the drywall tape non-uniformly so as to provide a maximum amount of adhesive along a center line of the tape.
Lamb discloses an adhesive drywall tape having a central projection on an outer or non-adhesive surface of the tape to cause a trowel for applying plaster over the tape to form a perfectly feathered edge.
Emal et al. disclose an adhesive drywall tape wherein the tape has a thickened center portion on an outer or non-adhesive surface thereof so that the non-adhesive surface becomes flat when the tape is applied to a joint.
Schold discloses an adhesive drywall tape wherein side edges of the drywall tape are buffed so that the side edges of the tape are thinner than the center of the tape whereby a finish coat of spackle can be applied over the side edges of the tape to obtain a smooth finish. In addition, Schold discloses a plastic bead on an inner or adhesive surface of the tape, the bead having raised portions for enhancing hinging action of the tape when the tape is applied to corner joints.
U.S. Pat. No. 1,039,363 to Chapin relates to an adhesive tape for joining abutting or adjacent edges or corners of paper boxes. The tape is formed of a narrow inner strip of tape and a wider outer strip of tape disposed over the inner strip. The inner and outer strips of tape are made of materials having different relative strengths, the inner strip being made of cloth and the outer strip being made of paper. The inner strip provides the primary staying power for securing the adjacent edges or corners while the outer strip hides and protects the inner strip and supplements the staying power of the inner strip. The outer strip also prevents the escape of adhesive on the inner strip, since such adhesive may be inclined to ooze through the inner strip.
None of the aforementioned patents recognize the significance of providing drywall tape with a non-uniform cross-section preventing the drywall tape from being drawn or sucked into the gaps and/or depressions formed at drywall joints. Furthermore, none of the aforementioned patents disclose an adhesive drywall tape utilizing a pre-applied yucca adhesive to reduce the time and materials required for wall finishing while providing an enhanced bond between the drywall tape and the drywall sheets. Applicators for facilitating the application of drywall tapes to drywall joints are also not disclosed by the aforementioned patents. In addition, the prior art does not teach the use of a yucca adhesive for securing drywall tape to sheets of drywall to save time and materials and to provide a better adhesive bond in wall finishing procedures.
In Costa Rica, yucca adhesive has been used as a poster adhesive and as a fabric starch. Until the present invention, however, the benefits and advantages of using yucca adhesive to secure drywall tape to sheets of drywall have not been recognized.
Accordingly, the need exists for an improved drywall tape having a configuration in cross-section to avoid drawing or sucking of the drywall tape into the gaps or grooves formed between abutting or adjacent edges of drywall sheets and/or into the depressions formed by adjacent or abutting xe2x80x9cfactory edgesxe2x80x9d of drywall sheets. The need further exists for drywall tapes, drywall tape applicators and methods of finishing drywall joints that eliminate the need for a xe2x80x9cbedding coatxe2x80x9d of joint compound, reduce the amount of joint compound to be applied over drywall tapes for xe2x80x9cblockingxe2x80x9d and xe2x80x9cskimmingxe2x80x9d, reduce the width of the band or stripe of joint compound to be applied for xe2x80x9cblockingxe2x80x9d, reduce the amount of time required for drywall tapes to become adhesively bonded to drywall sheets, provide a more secure adhesive bond between drywall tapes and drywall sheets, reduce construction costs by reducing the amount of materials and labor required, reduce the level of skill and expertise required to obtain high quality finished drywall joints, reduce the messiness or sloppiness associated with wall finishing, eliminate the need for toxic, non-biodegradable and inorganic adhesives, avoid peeling of drywall tapes and cracking of finished drywall joints and/or allow drywall tapes to be efficiently and quickly applied to drywall joints without wrinkling and without the formation of bubbles under the tapes.
Accordingly, it is a primary object of the present invention to overcome the aforementioned disadvantages of conventional drywall tapes, conventional drywall tape adhesives and conventional wall finishing techniques.
Another object of the present invention is to occupy a portion of the depression, formed along a drywall joint by adjacent or abutting xe2x80x9cfactory edgesxe2x80x9d of drywall sheets, with a thickened portion of a drywall tape applied over the joint.
A further object of the present invention is to prevent drywall tape applied over a drywall joint from being drawn into the depression created by sloping outer surface portions of adjacent or abutting drywall sheets forming the drywall joint.
The present invention has as another object to prevent drywall tape applied over a drywall joint from being drawn into the gap or groove between adjacent or abutting edges of drywall sheets forming the joint.
It is also an object of the present invention to eliminate the need for joint compound to affix drywall tape to a drywall joint.
An additional object of the present invention is to reduce the amount of materials and time needed for wall finishing.
The present invention has as a further object to reduce the drying time for drywall tape.
Another object of the present invention is to reduce the amount of time required for drywall tape to become firmly adhered to drywall sheets.
A still further object of the present invention is to reduce the width of a band of joint compound applied over drywall tape during xe2x80x9cblockingxe2x80x9d to obtain an imperceptible finished drywall joint.
Yet another object of the present invention is to utilize a pre-applied yucca adhesive in an adhesive drywall tape.
The present invention also has as an object to utilize a yucca adhesive to secure drywall tape to sheets of drywall.
Additionally, it is an object of the present invention to reduce the number of steps required to finish drywall joints.
The present invention has as a further object to reduce the level of skill and expertise needed to obtain high quality, finished drywall joints.
Moreover, it is an object of the present invention to increase the ease with which drywall tape is applied to drywall joints.
Another object of the present invention is to provide a drywall tape applicator facilitating the application of adhesive and non-adhesive drywall tapes to drywall joints.
It is also an object of the present invention to facilitate the application of adhesive drywall tape to drywall joints without wrinkling of the drywall tape and/or the formation of air bubbles under the drywall tape.
Yet an additional object of the present invention is to utilize a drywall tape applicator to wet an adhesive pre-applied on drywall tape within the applicator and to dispense the drywall tape from the applicator for securement to sheets of drywall via the pre-applied adhesive.
Still a further object of the present invention is to utilize a drywall tape applicator to apply an adhesive to drywall tape within the applicator and to dispense the drywall tape from the applicator for securement to sheets of drywall via the adhesive.
Some of the advantages of the present invention are that the drywall tapes can be formed from the same type of paper as that used for conventional paper drywall tapes, the drywall tapes are positioned over drywall joints in the same manner as conventional drywall tapes, the drywall tapes may have adhesives pre-applied thereto without requiring release sheets over the adhesives, the drywall tapes are simpler and easier to use than adhesive drywall tapes including release sheets, the drywall tapes may be supplied in rolls of varying lengths, the pre-applied adhesive is in a dry, non-activated state prior to use and is placed in an activated state by exposure to water, a roll of the drywall tape may be submerged in water to place the pre-applied adhesive in the activated state, the yucca adhesive used in the present invention is inexpensive and easy to prepare, the yucca adhesive is natural, organic and biodegradable, the yucca adhesive provides increased stiffness and adhesion, the drywall tapes can be used on flat drywall joints as well as inside and outside corner drywall joints, the drywall tapes can be applied to drywall joints under various environmental conditions without impairment of the finished joints, peeling and cracking of the finished joints are avoided, damage to the finished joints due to expansion and contraction of the wall or walls is avoided, the quantity or concentration of the yucca adhesive can be varied to obtain a desired tack or adhesion, the drywall tape applicators can be manually or electrically powered, the drywall tape applicators can be used to apply drywall tapes, with or without pre-applied adhesives, to drywall joints, the applicators can be used to activate pre-applied adhesives on the drywall tapes and/or to apply adhesive to the drywall tapes, the applicators can be designed to accommodate different size rolls of drywall tapes, the applicators can be used to apply drywall tapes to vertical as well as horizontal drywall joints, and the applicators can be adjustable for ease of use.
These and other objects, advantages and benefits are achieved with the present invention as generally characterized in a drywall tape including a narrow, paper tape of uniform width and non-uniform thickness or cross-section. The tape has a central portion of greater thickness or cross-section and side portions of lesser thickness or cross-section, together defining the non-uniform thickness or cross-section. The tape includes an outer planar surface and a non-planar inner surface. In one embodiment, the central portion and the side portions of the tape are formed integrally, unitarily, as a single strip of tape. In another embodiment, the tape is formed of inner and outer strips. The tape has a width slightly less than the width of a shallow depression formed by sloping outer surface portions of the drywall sheets along the drywall joint. Accordingly, the tape occupies the depression but does not protrude beyond non-sloping outer surface portions of the drywall sheets when the tape is applied over the joint. In addition, the central portion of the tape fills an inner portion of the depression and prevents the tape from being drawn or sucked into the depression and/or the gap between the edges of the drywall sheets. The drywall tape can be supplied as a non-adhesive drywall tape, to which an adhesive is applied or contacted during use, or as an adhesive drywall tape, to which an adhesive is pre-applied prior to use.
When the drywall tape is supplied as an adhesive drywall tape according to the present invention, a coating of dry, non-sticky, inactivated yucca adhesive is disposed on the inner surface of the drywall tape. The adhesive becomes sticky, tacky or activated when wet to adhere to sheets of drywall when the drywall tape is applied over a drywall joint formed by adjacent or abutting edges of the drywall sheets, respectively. The adhesive dries rapidly and stiffens as it dries to adhesively secure the drywall tape to the drywall sheets over the drywall joint. The yucca adhesive can be supplied separately from the drywall tapes, such as being supplied in powder form to be mixed with water or being supplied in fluid form pre-mixed with water, for use with non-adhesive drywall tapes.
A drywall tape applicator for applying drywall tapes to drywall joints in accordance with the present invention includes a housing and a handle attached to the housing. The handle is preferably adjustable in length and preferably disconnectable from the housing. The housing is adapted to receive a roll of drywall tape therein. The housing includes a fluid reservoir adapted to receive either a fluid for activating a pre-applied adhesive disposed on the drywall tape, or a fluidic adhesive for being applied to the drywall tape. Where the drywall tape has an inactivated, pre-applied adhesive thereon, fluid is supplied to the reservoir for wetting and thereby activating the adhesive. Where the drywall tape does not already have an adhesive thereon, a fluidic adhesive is supplied to the reservoir for being imparted to the drywall tape. The roll of drywall tape is rotatable within the enclosure to unroll or unwind the drywall tape such that the drywall tape, which has the pre-applied adhesive thereon activated or which has been exposed to the fluidic adhesive, passes through an open end of the housing to be dispensed or extended externally from the housing. The handle may be manipulated by a wall finisher to apply the drywall tape over the entire length of a drywall joint as it is dispensed from the housing.
A method of finishing a drywall joint according to the present invention includes the steps of positioning a length of paper drywall tape over a drywall joint with a width of the drywall tape substantially centered over the joint, securing the drywall tape over the joint with a yucca adhesive along the entire length of the joint, allowing the yucca adhesive to dry, applying a thin layer of joint compound over the drywall tape to blend the drywall tape into non-sloping outer surface portions of the drywall sheets, respectively, forming the joint, allowing the joint compound to dry and sanding the joint compound.
Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings, wherein like parts in each of the several figures are identified by the same reference characters.